Why do my hands go numb at night?
Understanding carpal tunnel syndrome, its causes and when treatment is necessary
Clinical contributor: Mr Ashley Simpson
Consultant Peripheral Nerve Surgeon
Waking in the middle of the night with numbness, tingling or discomfort in your hand can be unsettling. You may find yourself shaking your hand to restore sensation, only for the symptoms to return when you fall asleep.
One of the most common explanations is carpal tunnel syndrome. Although it is usually treatable, understanding what is happening to the nerve, and when to seek help, can make a considerable difference.
What is carpal tunnel syndrome?
The carpal tunnel is a narrow passageway at the wrist, formed by the small bones of the wrist and a strong ligament across its roof.
Several tendons pass through this tunnel, together with the median nerve. This nerve provides sensation to much of the thumb, index finger, middle finger and part of the ring finger. It also supplies several muscles responsible for thumb movement.
When pressure increases within the tunnel, the median nerve can become compressed.
Think of the nerve as an electrical cable passing through a narrow conduit. If the space around the cable becomes too tight, its ability to transmit signals can be disrupted.
Initially, this may cause intermittent tingling or numbness. With more prolonged or severe compression, persistent sensory changes and muscle weakness can develop.
- 1. Flexor retinaculum (transverse carpal ligament) – the roof of the tunnel
- 2. Median nerve – lies just beneath the roof, superficial to the tendons
- 3. Flexor tendons (nine): four superficial and four deep finger flexors, plus the long thumb flexor
- 4. Carpal bones – form the floor and side walls of the tunnel
Why are symptoms often worse at night?
Many people sleep with their wrists bent, sometimes without realising it.
This position can increase pressure within the carpal tunnel, aggravating compression of the median nerve.
Typical symptoms include:
- Tingling or numbness affecting the thumb, index and middle fingers, sometimes extending into the ring finger.
- Waking from sleep with an uncomfortable or numb hand.
- Shaking or hanging the hand over the side of the bed to relieve symptoms.
- Difficulty holding a telephone, steering wheel or book for prolonged periods.
- Dropping objects or struggling with fine movements.
Symptoms can affect one or both hands.
Importantly, numbness predominantly affecting the little finger is less characteristic of carpal tunnel syndrome and may indicate compression of a different nerve.
- 1. Palm side of the thumb, index and middle fingers and the thumb-side half of the ring finger
- 2. Little finger – not median nerve territory (unshaded)
- 3. Thenar eminence skin – unshaded: supplied by the palmar cutaneous branch, which arises proximal to (before) the tunnel
- 4. Back of the hand: only the fingertips and nail beds of the same digits
- 5. Rest of the back of the fingers and hand – unshaded
What causes it?
In many patients, there is no single identifiable cause.
Carpal tunnel syndrome can be associated with several factors, including diabetes, pregnancy, inflammatory arthritis and conditions affecting the thyroid gland.
Changes in the tissues surrounding the tendons can also reduce the available space within the tunnel.
Although repetitive hand activity may aggravate symptoms, it is not necessarily the underlying cause.
How is carpal tunnel syndrome diagnosed?
Diagnosis begins with a careful history and clinical examination.
The distribution of numbness, timing of symptoms and presence of weakness can often provide important clues.
A clinician may assess sensation, thumb muscle strength and whether particular wrist positions reproduce symptoms.
In some circumstances, nerve conduction studies are helpful. These measure how effectively electrical signals travel through the median nerve and can provide evidence of nerve compression at the wrist.
However, nerve conduction studies are not always necessary, particularly when the clinical diagnosis is clear.
They can be especially useful when symptoms are atypical, another nerve disorder is suspected or the severity of compression needs further assessment.
Does everyone need surgery?
No. Many patients can initially be managed without an operation.
The most appropriate treatment depends on symptom severity, duration and whether there is evidence of progressive nerve dysfunction.
Night splinting
A wrist splint worn during sleep helps maintain the wrist in a neutral position, reducing pressure on the median nerve.
This can be particularly effective for mild or intermittent symptoms.
Corticosteroid injection
An injection into the carpal tunnel can reduce inflammation and provide symptomatic relief.
For some patients, the improvement may be substantial, although symptoms can recur.
An injection does not necessarily provide a permanent solution to the underlying compression.
Surgery
Carpal tunnel decompression involves dividing the ligament forming the roof of the tunnel, increasing the space available for the median nerve.
The procedure is commonly performed under local anaesthesia, often as a day-case operation.
The aim is to relieve pressure on the nerve and prevent further deterioration.
Patients with intermittent symptoms may experience relatively rapid improvement, particularly in night-time tingling.
However, when compression has been severe or longstanding, recovery can be slower and may be incomplete.
When should I consider seeing a specialist?
Specialist assessment is particularly appropriate if:
- Symptoms regularly disturb your sleep despite appropriate splinting.
- Numbness becomes constant rather than intermittent.
- You notice increasing weakness or difficulty using your thumb.
- You are frequently dropping objects.
- Symptoms persist despite conservative treatment.
- The diagnosis remains uncertain.
Persistent numbness or progressive weakness should not simply be ignored. Prolonged nerve compression can sometimes result in irreversible damage.
Sudden weakness or numbness, particularly if accompanied by facial weakness, speech disturbance or other neurological symptoms, requires emergency assessment rather than a routine carpal tunnel consultation.
Could the problem be coming from somewhere else?
Yes, and this is an important consideration.
Not every patient with hand numbness has carpal tunnel syndrome.
Other possible causes include compression of the ulnar nerve at the elbow, nerve irritation originating from the cervical spine, and more generalised peripheral nerve disorders.
Occasionally, more than one problem may coexist.
This is why identifying the correct diagnosis is more important than simply treating the location where symptoms are felt.
How can Elite Musculoskeletal Concierge help?
At Elite Musculoskeletal Concierge, we recognise that patients do not always know which specialist they need to see.
Hand numbness may originate from the wrist, elbow, neck or elsewhere within the nervous system.
Our consultant-led approach helps establish the most appropriate next step, coordinating access to specialist assessment, relevant investigations and treatment where indicated.
Through our network, patients can access expertise in hand surgery, peripheral nerve surgery and spinal conditions without having to navigate multiple referral pathways independently.
You do not need to know which specialist you need. That is our job.
Clinical attribution: Mr Ashley Simpson, Consultant Peripheral Nerve Surgeon. Adapted for the Elite Musculoskeletal Concierge patient education library. This article provides general information and does not replace individual medical assessment.